No Technical Reason to Prohibit the Use of Mobile Phones at Petrol Stations

Ongoing media reports fuelled by hoax internet warnings have led to public concern that mobile phones are a high risk when used at petrol stations; however, there is no sound technical basis to prohibit the use of mobile phones at petrol stations or single them out as hazards.

The amount of radio frequency energy emitted from modern hand-held mobile phones is too low to cause a spark, which could ignite petrol fumes. Shell UK Oil assessed the risks of a radio frequency spark from mobile phones in 1991[1] and said:

…portable cellphones properly used do not represent a meaningful hazard on the retail forecourt. Without doubt, apart from the human acts of smoking and striking a match, the thing that represents the greatest hazard on the retail forecourt is the motorcar!

There have been media reports of incidents, however, upon further investigation; these have turned out to be false. Alleged incidents are often based on a hoax email ‘warning’, which falsely claims to be from Shell Chemicals and includes a number of completely fictitious incidents.

The concern about mobile phone use at petrol stations was based on the belief that there was a risk the battery may become dislodged and cause a spark that may ignite fuel; although, no one had any credible evidence to support this opinion.

Consequently, some oil companies warn customers that any battery operated electronic device should be turned off and not used at petrol stations.

The most recent study[2] published in 2007, concluded that it is body static and not mobile phones that cause petrol station fires. The report concluded:

Investigations have identified the real cause; body static generated through vehicle re-entry while refuelling. This episode suggests the need for clarity about the precise reasons behind any restriction on the use of a popular device that is already established as a potential, but invariably unconfirmed, health hazard.

Furthermore, the report says that the pre-emptive ban on mobile phones at petrol stations has resulted in a delay in the identification of the real cause of fires at petrol stations. The report states:

Among a number of problematic consequences, most ironic has been to distract from the real cause of the increased number of fires at, particularly, American petrol stations.

Additionally, two research papers have specifically considered the spark discharge risk for mobile phones (i.e. pressing buttons, disconnecting the battery, vibrator mode, accidental shorting of the battery terminals and electrostatic discharge) and have concluded that this is highly unlikely.

A 1999 report[3] by Exponent Failure Analysis Associates in the USA concluded that “the use of a cell phone at a gasoline filling station under normal operating conditions presents a negligible hazard” and that the likelihood of such an accident under any conditions “is very remote”.

The report also stated:

“Automobiles (which have numerous potential ignition sources) pose a greater ignition hazard,” and “Finally, other potential ignition sources are present, such as static discharge between a person and a vehicle.”

An analysis[4] by the Centre for the Study of Wireless Electromagnetic Compatibility Centre at the University of Oklahoma reached a similar conclusion in August 2001. It said research into this issue “provided virtually no evidence to suggest that cell phones pose a hazard at gas stations.”

While it may be theoretically possible for a spark from a cell phone battery to ignite gas vapour under very precise conditions, the historical evidence does not support the need for further research. 

Until there is evidence to the contrary, we suggest that no further action be initiated in this regard, and that no recommendations for further action are required of the wireless phone or petroleum industries.

This research is supported by the fact that there has been no actual incident of fuel ignition at petrol stations that has been demonstrated to have been caused by mobile phone use, anywhere in the world.

Following a recent seminar on this topic by the British Institute of Petroleum, they announced in a press release[5] that:

The seminar showed the findings of research undertaken to date demonstrating that although the majority of mobile phones are not specifically designed and constructed to prevent them igniting a flammable atmosphere (in accordance with standards for ‘protected equipment’), the risk they present as a source of ignition is negligible.

While not entirely scientific study, US television show Mythbusters has twice investigated these claims. In season 1 episode 2 and season 2 episode 14, the Mythbusters team concluded:

A properly-working cell phone poses almost no danger of igniting gasoline, even when surrounded by gasoline vapor with the optimum fuel-air mix for ignition. The actual risk comes from an electrostatic discharge between a charged driver and the car, often a result of continually getting into and out of the vehicle.

UK television show Brainiac also came to a similar conclusion. The video of the experiment can be seen here.

While mobile phone users should always obey warning signs, there is no sound technical basis to prohibit the use of mobile phones in petrol stations or single them out as hazards.

[1] Radio telephones in cabs – avoiding the big bang: Petroleum Review; pp 337 – 339 July, 1991.
[2] Real and phantom risks at the petrol station: The curious case of mobile phones, fires and body static; Burgess A. University of Kent, UK, March 2007 http://www.informaworld.com/smpp/1218702584-27924143/content~content=a772395372~tab=send
[3] Cell Phone Usage at Gasoline Stations: Exponent Failure Analysis Associates; Menlo Park, California USA, December 1999.
[4] Investigation of the Potential for Wireless Phones to Cause Explosions at Gas Stations; Center for the Study of Wireless Electromagnetic Compatibility, University of Oklahoma, Norman, Oklahoma USA August, 2001. www.ou.edu/engineering/emc/
[5] Ignition of Flammable Vapour by Mobile Phones Not Substantiated by Technical Evidence: Statement of the Institute of Petroleum; March 21, 2003. www.intellectuk.org/press/news/news_21_03_03.asp